Teams time allocation

As a team leader and a Project manager/Principal manager you are probably wondering how to allocate your teams time.
The article, How intranet teams should spend their time, is very interesting and you may find it a nice guideline that may help you in establishing the same in your business.
The time division may not be for your liking or you may want different task definition but the idea that urgent things cannot occupy 100% of your time and the team needs some time on new things or just to base relations.
But that is not a new idea.
Why then did it become extinct?